Linaro-mm-sig April 2021

linaro-mm-sig@lists.linaro.org

13 participants
42 discussions

Re: [Linaro-mm-sig] [PATCH v4] dma-buf: Add DmaBufTotal counter in meminfo

by Christian König

Am 20.04.21 um 09:04 schrieb Michal Hocko: > On Mon 19-04-21 18:37:13, Christian König wrote: >> Am 19.04.21 um 18:11 schrieb Michal Hocko: > [...] >>> The question is not whether it is NUMA aware but whether it is useful to >>> know per-numa data for the purpose the counter is supposed to serve. >> No, not at all. The pages of a single DMA-buf could even be from different >> NUMA nodes if the exporting driver decides that this is somehow useful. > As the use of the counter hasn't been explained yet I can only > speculate. One thing that I can imagine to be useful is to fill gaps in > our accounting. It is quite often that the memroy accounted in > /proc/meminfo (or oom report) doesn't add up to the overall memory > usage. In some workloads the workload can be huge! In many cases there > are other means to find out additional memory by a subsystem specific > interfaces (e.g. networking buffers). I do assume that dma-buf is just > one of those and the counter can fill the said gap at least partially > for some workloads. That is definitely useful. Yes, completely agree. I'm just not 100% sure if the DMA-buf framework should account for that or the individual drivers exporting DMA-bufs. See below for a further explanation. > What I am trying to bring up with NUMA side is that the same problem can > happen on per-node basis. Let's say that some user consumes unexpectedly > large amount of dma-buf on a certain node. This can lead to observable > performance impact on anybody on allocating from that node and even > worse cause an OOM for node bound consumers. How do I find out that it > was dma-buf that has caused the problem? Yes, that is the direction my thinking goes as well, but also even further. See DMA-buf is also used to share device local memory between processes as well. In other words VRAM on graphics hardware. On my test system here I have 32GB of system memory and 16GB of VRAM. I can use DMA-buf to allocate that 16GB of VRAM quite easily which then shows up under /proc/meminfo as used memory. But that isn't really system memory at all, it's just allocated device memory. > See where I am heading? Yeah, totally. Thanks for pointing this out. Suggestions how to handle that? Regards, Christian.

3 years, 8 months

Re: [Linaro-mm-sig] [PATCH v4] dma-buf: Add DmaBufTotal counter in meminfo

by Christian König

Am 19.04.21 um 18:11 schrieb Michal Hocko: > On Mon 19-04-21 17:44:13, Christian König wrote: >> Am 19.04.21 um 17:19 schrieb Peter.Enderborg(a)sony.com: >>> On 4/19/21 5:00 PM, Michal Hocko wrote: >>>> On Mon 19-04-21 12:41:58, Peter.Enderborg(a)sony.com wrote: >>>>> On 4/19/21 2:16 PM, Michal Hocko wrote: >>>>>> On Sat 17-04-21 12:40:32, Peter Enderborg wrote: >>>>>>> This adds a total used dma-buf memory. Details >>>>>>> can be found in debugfs, however it is not for everyone >>>>>>> and not always available. dma-buf are indirect allocated by >>>>>>> userspace. So with this value we can monitor and detect >>>>>>> userspace applications that have problems. >>>>>> The changelog would benefit from more background on why this is needed, >>>>>> and who is the primary consumer of that value. >>>>>> >>>>>> I cannot really comment on the dma-buf internals but I have two remarks. >>>>>> Documentation/filesystems/proc.rst needs an update with the counter >>>>>> explanation and secondly is this information useful for OOM situations >>>>>> analysis? If yes then show_mem should dump the value as well. >>>>>> >>>>>> From the implementation point of view, is there any reason why this >>>>>> hasn't used the existing global_node_page_state infrastructure? >>>>> I fix doc in next version. Im not sure what you expect the commit message to include. >>>> As I've said. Usual justification covers answers to following questions >>>> - Why do we need it? >>>> - Why the existing data is insuficient? >>>> - Who is supposed to use the data and for what? >>>> >>>> I can see an answer for the first two questions (because this can be a >>>> lot of memory and the existing infrastructure is not production suitable >>>> - debugfs). But the changelog doesn't really explain who is going to use >>>> the new data. Is this a monitoring to raise an early alarm when the >>>> value grows? Is this for debugging misbehaving drivers? How is it >>>> valuable for those? >>>> >>>>> The function of the meminfo is: (From Documentation/filesystems/proc.rst) >>>>> >>>>> "Provides information about distribution and utilization of memory." >>>> True. Yet we do not export any random counters, do we? >>>> >>>>> Im not the designed of dma-buf, I think global_node_page_state as a kernel >>>>> internal. >>>> It provides a node specific and optimized counters. Is this a good fit >>>> with your new counter? Or the NUMA locality is of no importance? >>> Sounds good to me, if Christian Koenig think it is good, I will use that. >>> It is only virtio in drivers that use the global_node_page_state if >>> that matters. >> DMA-buf are not NUMA aware at all. On which node the pages are allocated >> (and if we use pages at all and not internal device memory) is up to the >> exporter and importer. > The question is not whether it is NUMA aware but whether it is useful to > know per-numa data for the purpose the counter is supposed to serve. No, not at all. The pages of a single DMA-buf could even be from different NUMA nodes if the exporting driver decides that this is somehow useful. Christian.

3 years, 8 months

Re: [Linaro-mm-sig] [PATCH v4] dma-buf: Add DmaBufTotal counter in meminfo

by Christian König

Am 19.04.21 um 17:19 schrieb Peter.Enderborg(a)sony.com: > On 4/19/21 5:00 PM, Michal Hocko wrote: >> On Mon 19-04-21 12:41:58, Peter.Enderborg(a)sony.com wrote: >>> On 4/19/21 2:16 PM, Michal Hocko wrote: >>>> On Sat 17-04-21 12:40:32, Peter Enderborg wrote: >>>>> This adds a total used dma-buf memory. Details >>>>> can be found in debugfs, however it is not for everyone >>>>> and not always available. dma-buf are indirect allocated by >>>>> userspace. So with this value we can monitor and detect >>>>> userspace applications that have problems. >>>> The changelog would benefit from more background on why this is needed, >>>> and who is the primary consumer of that value. >>>> >>>> I cannot really comment on the dma-buf internals but I have two remarks. >>>> Documentation/filesystems/proc.rst needs an update with the counter >>>> explanation and secondly is this information useful for OOM situations >>>> analysis? If yes then show_mem should dump the value as well. >>>> >>>> From the implementation point of view, is there any reason why this >>>> hasn't used the existing global_node_page_state infrastructure? >>> I fix doc in next version. Im not sure what you expect the commit message to include. >> As I've said. Usual justification covers answers to following questions >> - Why do we need it? >> - Why the existing data is insuficient? >> - Who is supposed to use the data and for what? >> >> I can see an answer for the first two questions (because this can be a >> lot of memory and the existing infrastructure is not production suitable >> - debugfs). But the changelog doesn't really explain who is going to use >> the new data. Is this a monitoring to raise an early alarm when the >> value grows? Is this for debugging misbehaving drivers? How is it >> valuable for those? >> >>> The function of the meminfo is: (From Documentation/filesystems/proc.rst) >>> >>> "Provides information about distribution and utilization of memory." >> True. Yet we do not export any random counters, do we? >> >>> Im not the designed of dma-buf, I think global_node_page_state as a kernel >>> internal. >> It provides a node specific and optimized counters. Is this a good fit >> with your new counter? Or the NUMA locality is of no importance? > Sounds good to me, if Christian Koenig think it is good, I will use that. > It is only virtio in drivers that use the global_node_page_state if > that matters. DMA-buf are not NUMA aware at all. On which node the pages are allocated (and if we use pages at all and not internal device memory) is up to the exporter and importer. Christian. > > >>> dma-buf is a device driver that provides a function so I might be >>> on the outside. However I also see that it might be relevant for a OOM. >>> It is memory that can be freed by killing userspace processes. >>> >>> The show_mem thing. Should it be a separate patch? >> This is up to you but if you want to expose the counter then send it in >> one series. >>

3 years, 8 months

Re: [Linaro-mm-sig] [PATCH] ASoC: fsl: imx-pcm-dma: Don't request dma channel in probe

by Lucas Stach

Am Montag, dem 19.04.2021 um 07:17 +0000 schrieb Robin Gong: > Hi Lucas, > > On 2021/04/14 Lucas Stach <l.stach(a)pengutronix.de> wrote: > > Hi Robin, > > > > Am Mittwoch, dem 14.04.2021 um 14:33 +0000 schrieb Robin Gong: > > > On 2020/05/20 17:43 Lucas Stach <l.stach(a)pengutronix.de> wrote: > > > > Am Mittwoch, den 20.05.2020, 16:20 +0800 schrieb Shengjiu Wang: > > > > > Hi > > > > > > > > > > On Tue, May 19, 2020 at 6:04 PM Lucas Stach > > > > > <l.stach(a)pengutronix.de> > > > > wrote: > > > > > > Am Dienstag, den 19.05.2020, 17:41 +0800 schrieb Shengjiu Wang: > > > > > > > There are two requirements that we need to move the request of > > > > > > > dma channel from probe to open. > > > > > > > > > > > > How do you handle -EPROBE_DEFER return code from the channel > > > > > > request if you don't do it in probe? > > > > > > > > > > I use the dma_request_slave_channel or dma_request_channel instead > > > > > of dmaengine_pcm_request_chan_of. so there should be not > > > > > -EPROBE_DEFER return code. > > > > > > > > This is a pretty weak argument. The dmaengine device might probe > > > > after you try to get the channel. Using a function to request the > > > > channel that doesn't allow you to handle probe deferral is IMHO a > > > > bug and should be fixed, instead of building even more assumptions on top > > of it. > > > > > > > > > > > - When dma device binds with power-domains, the power will be > > > > > > > enabled when we request dma channel. If the request of dma > > > > > > > channel happen on probe, then the power-domains will be always > > > > > > > enabled after kernel boot up, which is not good for power > > > > > > > saving, so we need to move the request of dma channel to > > > > > > > .open(); > > > > > > > > > > > > This is certainly something which could be fixed in the > > > > > > dmaengine driver. > > > > > > > > > > Dma driver always call the pm_runtime_get_sync in > > > > > device_alloc_chan_resources, the device_alloc_chan_resources is > > > > > called when channel is requested. so power is enabled on channel > > request. > > > > > > > > So why can't you fix the dmaengine driver to do that RPM call at a > > > > later time when the channel is actually going to be used? This will > > > > allow further power savings with other slave devices than the audio PCM. > > > Hi Lucas, > > > Thanks for your suggestion. I have tried to implement runtime > > > autosuspend in fsl-edma driver on i.mx8qm/qxp with delay time (2 sec) > > > for this feature as below (or you can refer to > > > drivers/dma/qcom/hidma.c), and pm_runtime_get_sync/ > > > pm_runtime_put_autosuspend in all dmaengine driver interface like > > > device_alloc_chan_resources/device_prep_slave_sg/device_prep_dma_cycli > > > c/ > > > device_tx_status... > > > > > > > > > pm_runtime_use_autosuspend(fsl_chan->dev); > > > pm_runtime_set_autosuspend_delay(fsl_chan->dev, > > 2000); > > > > > > That could resolve this audio case since the autosuspend could suspend > > > runtime after > > > 2 seconds if there is no further dma transfer but only channel > > request(device_alloc_chan_resources). > > > But unfortunately, it cause another issue. As you know, on our > > > i.mx8qm/qxp, power domain done by scfw (drivers/firmware/imx/scu-pd.c) > > over mailbox: > > > imx_sc_pd_power()->imx_scu_call_rpc()-> > > > imx_scu_ipc_write()->mbox_send_message() > > > which means have to 'waits for completion', meanwhile, some driver > > > like tty will call dmaengine interfaces in non-atomic case as below, > > > > > > static int uart_write(struct tty_struct *tty, const unsigned char > > > *buf, int count) { > > > ....... > > > port = uart_port_lock(state, flags); > > > ...... > > > __uart_start(tty); //call start_tx()->dmaengine_prep_slave_sg... > > > uart_port_unlock(port, flags); > > > return ret; > > > } > > > > > > Thus dma runtime resume may happen in that timing window and cause > > kernel alarm. > > > I'm not sure whether there are similar limitations on other driver > > > subsystem. But for me, It looks like the only way to resolve the > > > contradiction between tty and scu-pd (hardware limitation on > > > i.mx8qm/qxp) is to give up autosuspend and keep pm_runtime_get_sync > > only in device_alloc_chan_resources because request channel is a safe > > non-atomic phase. > > > Do you have any idea? Thanks in advance. > > > > If you look closely at the driver you used as an example (hidma.c) it looks like > > there is already something in there, which looks very much like what you need > > here: > > > > In hidma_issue_pending() the driver tries to get the device to runtime resume. > > If this doesn't work, maybe due to the power domain code not being able to > > be called in atomic context, the actual work of waking up the dma hardware > > and issuing the descriptor is shunted to a tasklet. > > > > If I'm reading this right, this is exactly what you need here to be able to call the > > dmaengine code from atomic context: try the rpm get and issue immediately > > when possible, otherwise shunt the work to a non- atomic context where you > > can deal with the requirements of scu-pd. > Yes, I can schedule_work to worker to runtime resume edma channel by calling scu-pd. > But that means all dmaengine interfaces should be taken care, not only issue_pending() > but also dmaengine_terminate_all()/dmaengine_pause()/dmaengine_resume()/ > dmaengine_tx_status(). Not sure why hidma only take care issue_pending. Maybe > their user case is just for memcpy/memset so that no further complicate case as ALSA > or TTY. > Besides, for autosuspend in cyclic, we have to add pm_runtime_get_sync into interrupt > handler as qcom/bam_dma.c. but how could resolve the scu-pd's non-atmoic limitation > in interrupt handler? Sure, this all needs some careful analysis on how those functions are called and what to do about atomic callers, but it should be doable. I don't see any fundamental issues here. I don't see why you would ever need to wake the hardware in an interrupt handler. Surely the hardware is already awake, as it wouldn't signal an interrupt otherwise. And for the issue with scu-pd you only care about the state transition of suspended->running. If the hardware is already running/awake, the runtime pm state handling is nothing more than bumping a refcount, which is atomic safe. Putting the HW in suspend is already handled asynchronously in a worker, so this is also atomic safe. Regards, Lucas

3 years, 8 months

Re: [Linaro-mm-sig] [External] [PATCH v4] dma-buf: Add DmaBufTotal counter in meminfo

by Christian König

Am 17.04.21 um 16:21 schrieb Muchun Song: > On Sat, Apr 17, 2021 at 9:44 PM <Peter.Enderborg(a)sony.com> wrote: >> On 4/17/21 3:07 PM, Muchun Song wrote: >>> On Sat, Apr 17, 2021 at 6:41 PM Peter Enderborg >>> <peter.enderborg(a)sony.com> wrote: >>>> This adds a total used dma-buf memory. Details >>>> can be found in debugfs, however it is not for everyone >>>> and not always available. dma-buf are indirect allocated by >>>> userspace. So with this value we can monitor and detect >>>> userspace applications that have problems. >>>> >>>> Signed-off-by: Peter Enderborg <peter.enderborg(a)sony.com> >>>> --- >>>> drivers/dma-buf/dma-buf.c | 13 +++++++++++++ >>>> fs/proc/meminfo.c | 5 ++++- >>>> include/linux/dma-buf.h | 1 + >>>> 3 files changed, 18 insertions(+), 1 deletion(-) >>>> >>>> diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c >>>> index f264b70c383e..197e5c45dd26 100644 >>>> --- a/drivers/dma-buf/dma-buf.c >>>> +++ b/drivers/dma-buf/dma-buf.c >>>> @@ -37,6 +37,7 @@ struct dma_buf_list { >>>> }; >>>> >>>> static struct dma_buf_list db_list; >>>> +static atomic_long_t dma_buf_global_allocated; >>>> >>>> static char *dmabuffs_dname(struct dentry *dentry, char *buffer, int buflen) >>>> { >>>> @@ -79,6 +80,7 @@ static void dma_buf_release(struct dentry *dentry) >>>> if (dmabuf->resv == (struct dma_resv *)&dmabuf[1]) >>>> dma_resv_fini(dmabuf->resv); >>>> >>>> + atomic_long_sub(dmabuf->size, &dma_buf_global_allocated); >>>> module_put(dmabuf->owner); >>>> kfree(dmabuf->name); >>>> kfree(dmabuf); >>>> @@ -586,6 +588,7 @@ struct dma_buf *dma_buf_export(const struct dma_buf_export_info *exp_info) >>>> mutex_lock(&db_list.lock); >>>> list_add(&dmabuf->list_node, &db_list.head); >>>> mutex_unlock(&db_list.lock); >>>> + atomic_long_add(dmabuf->size, &dma_buf_global_allocated); >>>> >>>> return dmabuf; >>>> >>>> @@ -1346,6 +1349,16 @@ void dma_buf_vunmap(struct dma_buf *dmabuf, struct dma_buf_map *map) >>>> } >>>> EXPORT_SYMBOL_GPL(dma_buf_vunmap); >>>> >>>> +/** >>>> + * dma_buf_allocated_pages - Return the used nr of pages >>>> + * allocated for dma-buf >>>> + */ >>>> +long dma_buf_allocated_pages(void) >>>> +{ >>>> + return atomic_long_read(&dma_buf_global_allocated) >> PAGE_SHIFT; >>>> +} >>>> +EXPORT_SYMBOL_GPL(dma_buf_allocated_pages); >>> dma_buf_allocated_pages is only called from fs/proc/meminfo.c. >>> I am confused why it should be exported. If it won't be called >>> from the driver module, we should not export it. >> Ah. I thought you did not want the GPL restriction. I don't have real >> opinion about it. It's written to be following the rest of the module. >> It is not needed for the usage of dma-buf in kernel module. But I >> don't see any reason for hiding it either. > The modules do not need dma_buf_allocated_pages, hiding it > can prevent the module from calling it. So I think that > EXPORT_SYMBOL_GPL is unnecessary. If one day someone > want to call it from the module, maybe it’s not too late to export > it at that time. Yeah, that is a rather good point. Only symbols which should be used by modules/drivers should be exported. Christian. > >> >>> Thanks. >>> >>>> + >>>> #ifdef CONFIG_DEBUG_FS >>>> static int dma_buf_debug_show(struct seq_file *s, void *unused) >>>> { >>>> diff --git a/fs/proc/meminfo.c b/fs/proc/meminfo.c >>>> index 6fa761c9cc78..ccc7c40c8db7 100644 >>>> --- a/fs/proc/meminfo.c >>>> +++ b/fs/proc/meminfo.c >>>> @@ -16,6 +16,7 @@ >>>> #ifdef CONFIG_CMA >>>> #include <linux/cma.h> >>>> #endif >>>> +#include <linux/dma-buf.h> >>>> #include <asm/page.h> >>>> #include "internal.h" >>>> >>>> @@ -145,7 +146,9 @@ static int meminfo_proc_show(struct seq_file *m, void *v) >>>> show_val_kb(m, "CmaFree: ", >>>> global_zone_page_state(NR_FREE_CMA_PAGES)); >>>> #endif >>>> - >>>> +#ifdef CONFIG_DMA_SHARED_BUFFER >>>> + show_val_kb(m, "DmaBufTotal: ", dma_buf_allocated_pages()); >>>> +#endif >>>> hugetlb_report_meminfo(m); >>>> >>>> arch_report_meminfo(m); >>>> diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h >>>> index efdc56b9d95f..5b05816bd2cd 100644 >>>> --- a/include/linux/dma-buf.h >>>> +++ b/include/linux/dma-buf.h >>>> @@ -507,4 +507,5 @@ int dma_buf_mmap(struct dma_buf *, struct vm_area_struct *, >>>> unsigned long); >>>> int dma_buf_vmap(struct dma_buf *dmabuf, struct dma_buf_map *map); >>>> void dma_buf_vunmap(struct dma_buf *dmabuf, struct dma_buf_map *map); >>>> +long dma_buf_allocated_pages(void); >>>> #endif /* __DMA_BUF_H__ */ >>>> -- >>>> 2.17.1 >>>>

3 years, 8 months

Re: [Linaro-mm-sig] [PATCH v4] dma-buf: Add DmaBufTotal counter in meminfo

by Christian König

Am 17.04.21 um 12:40 schrieb Peter Enderborg: > This adds a total used dma-buf memory. Details > can be found in debugfs, however it is not for everyone > and not always available. dma-buf are indirect allocated by > userspace. So with this value we can monitor and detect > userspace applications that have problems. > > Signed-off-by: Peter Enderborg <peter.enderborg(a)sony.com> Reviewed-by: Christian König <christian.koenig(a)amd.com> How do you want to upstream this? > --- > drivers/dma-buf/dma-buf.c | 13 +++++++++++++ > fs/proc/meminfo.c | 5 ++++- > include/linux/dma-buf.h | 1 + > 3 files changed, 18 insertions(+), 1 deletion(-) > > diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c > index f264b70c383e..197e5c45dd26 100644 > --- a/drivers/dma-buf/dma-buf.c > +++ b/drivers/dma-buf/dma-buf.c > @@ -37,6 +37,7 @@ struct dma_buf_list { > }; > > static struct dma_buf_list db_list; > +static atomic_long_t dma_buf_global_allocated; > > static char *dmabuffs_dname(struct dentry *dentry, char *buffer, int buflen) > { > @@ -79,6 +80,7 @@ static void dma_buf_release(struct dentry *dentry) > if (dmabuf->resv == (struct dma_resv *)&dmabuf[1]) > dma_resv_fini(dmabuf->resv); > > + atomic_long_sub(dmabuf->size, &dma_buf_global_allocated); > module_put(dmabuf->owner); > kfree(dmabuf->name); > kfree(dmabuf); > @@ -586,6 +588,7 @@ struct dma_buf *dma_buf_export(const struct dma_buf_export_info *exp_info) > mutex_lock(&db_list.lock); > list_add(&dmabuf->list_node, &db_list.head); > mutex_unlock(&db_list.lock); > + atomic_long_add(dmabuf->size, &dma_buf_global_allocated); > > return dmabuf; > > @@ -1346,6 +1349,16 @@ void dma_buf_vunmap(struct dma_buf *dmabuf, struct dma_buf_map *map) > } > EXPORT_SYMBOL_GPL(dma_buf_vunmap); > > +/** > + * dma_buf_allocated_pages - Return the used nr of pages > + * allocated for dma-buf > + */ > +long dma_buf_allocated_pages(void) > +{ > + return atomic_long_read(&dma_buf_global_allocated) >> PAGE_SHIFT; > +} > +EXPORT_SYMBOL_GPL(dma_buf_allocated_pages); > + > #ifdef CONFIG_DEBUG_FS > static int dma_buf_debug_show(struct seq_file *s, void *unused) > { > diff --git a/fs/proc/meminfo.c b/fs/proc/meminfo.c > index 6fa761c9cc78..ccc7c40c8db7 100644 > --- a/fs/proc/meminfo.c > +++ b/fs/proc/meminfo.c > @@ -16,6 +16,7 @@ > #ifdef CONFIG_CMA > #include <linux/cma.h> > #endif > +#include <linux/dma-buf.h> > #include <asm/page.h> > #include "internal.h" > > @@ -145,7 +146,9 @@ static int meminfo_proc_show(struct seq_file *m, void *v) > show_val_kb(m, "CmaFree: ", > global_zone_page_state(NR_FREE_CMA_PAGES)); > #endif > - > +#ifdef CONFIG_DMA_SHARED_BUFFER > + show_val_kb(m, "DmaBufTotal: ", dma_buf_allocated_pages()); > +#endif > hugetlb_report_meminfo(m); > > arch_report_meminfo(m); > diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h > index efdc56b9d95f..5b05816bd2cd 100644 > --- a/include/linux/dma-buf.h > +++ b/include/linux/dma-buf.h > @@ -507,4 +507,5 @@ int dma_buf_mmap(struct dma_buf *, struct vm_area_struct *, > unsigned long); > int dma_buf_vmap(struct dma_buf *dmabuf, struct dma_buf_map *map); > void dma_buf_vunmap(struct dma_buf *dmabuf, struct dma_buf_map *map); > +long dma_buf_allocated_pages(void); > #endif /* __DMA_BUF_H__ */

3 years, 8 months

Re: [Linaro-mm-sig] [PATCH v2] dma-buf: Add DmaBufTotal counter in meminfo

by Christian König

Am 16.04.21 um 14:33 schrieb Peter Enderborg: > This adds a total used dma-buf memory. Details > can be found in debugfs, however it is not for everyone > and not always available. dma-buf are indirect allocated by > userspace. So with this value we can monitor and detect > userspace applications that have problems. > > Signed-off-by: Peter Enderborg <peter.enderborg(a)sony.com> > --- > drivers/dma-buf/dma-buf.c | 12 ++++++++++++ > fs/proc/meminfo.c | 5 ++++- > include/linux/dma-buf.h | 1 + > 3 files changed, 17 insertions(+), 1 deletion(-) > > diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c > index f264b70c383e..9f88171b394c 100644 > --- a/drivers/dma-buf/dma-buf.c > +++ b/drivers/dma-buf/dma-buf.c > @@ -37,6 +37,7 @@ struct dma_buf_list { > }; > > static struct dma_buf_list db_list; > +static atomic_long_t dma_buf_size; Probably better to call this and the get function something like global_allocated. Christian. > > static char *dmabuffs_dname(struct dentry *dentry, char *buffer, int buflen) > { > @@ -79,6 +80,7 @@ static void dma_buf_release(struct dentry *dentry) > if (dmabuf->resv == (struct dma_resv *)&dmabuf[1]) > dma_resv_fini(dmabuf->resv); > > + atomic_long_sub(dmabuf->size, &dma_buf_size); > module_put(dmabuf->owner); > kfree(dmabuf->name); > kfree(dmabuf); > @@ -586,6 +588,7 @@ struct dma_buf *dma_buf_export(const struct dma_buf_export_info *exp_info) > mutex_lock(&db_list.lock); > list_add(&dmabuf->list_node, &db_list.head); > mutex_unlock(&db_list.lock); > + atomic_long_add(dmabuf->size, &dma_buf_size); > > return dmabuf; > > @@ -1346,6 +1349,15 @@ void dma_buf_vunmap(struct dma_buf *dmabuf, struct dma_buf_map *map) > } > EXPORT_SYMBOL_GPL(dma_buf_vunmap); > > +/** > + * dma_buf_get_size - Return the used nr pages by dma-buf > + */ > +long dma_buf_get_size(void) > +{ > + return atomic_long_read(&dma_buf_size) >> PAGE_SHIFT; > +} > +EXPORT_SYMBOL_GPL(dma_buf_get_size); > + > #ifdef CONFIG_DEBUG_FS > static int dma_buf_debug_show(struct seq_file *s, void *unused) > { > diff --git a/fs/proc/meminfo.c b/fs/proc/meminfo.c > index 6fa761c9cc78..178f6ffb1618 100644 > --- a/fs/proc/meminfo.c > +++ b/fs/proc/meminfo.c > @@ -16,6 +16,7 @@ > #ifdef CONFIG_CMA > #include <linux/cma.h> > #endif > +#include <linux/dma-buf.h> > #include <asm/page.h> > #include "internal.h" > > @@ -145,7 +146,9 @@ static int meminfo_proc_show(struct seq_file *m, void *v) > show_val_kb(m, "CmaFree: ", > global_zone_page_state(NR_FREE_CMA_PAGES)); > #endif > - > +#ifdef CONFIG_DMA_SHARED_BUFFER > + show_val_kb(m, "DmaBufTotal: ", dma_buf_get_size()); > +#endif > hugetlb_report_meminfo(m); > > arch_report_meminfo(m); > diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h > index efdc56b9d95f..f6481315a377 100644 > --- a/include/linux/dma-buf.h > +++ b/include/linux/dma-buf.h > @@ -507,4 +507,5 @@ int dma_buf_mmap(struct dma_buf *, struct vm_area_struct *, > unsigned long); > int dma_buf_vmap(struct dma_buf *dmabuf, struct dma_buf_map *map); > void dma_buf_vunmap(struct dma_buf *dmabuf, struct dma_buf_map *map); > +long dma_buf_get_size(void); > #endif /* __DMA_BUF_H__ */

3 years, 8 months

Re: [Linaro-mm-sig] [PATCH] dma-buf: Add DmaBufTotal counter in meminfo

by Christian König

Am 16.04.21 um 11:37 schrieb Peter Enderborg: > This adds a total used dma-buf memory. Details > can be found in debugfs, however it is not for everyone > and not always available. Well you are kind of missing the intention here. I mean knowing this is certainly useful in some case, but you need to describe which cases that are. Christian. > > Signed-off-by: Peter Enderborg <peter.enderborg(a)sony.com> > --- > drivers/dma-buf/dma-buf.c | 12 ++++++++++++ > fs/proc/meminfo.c | 2 ++ > include/linux/dma-buf.h | 1 + > 3 files changed, 15 insertions(+) > > diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c > index f264b70c383e..9f88171b394c 100644 > --- a/drivers/dma-buf/dma-buf.c > +++ b/drivers/dma-buf/dma-buf.c > @@ -37,6 +37,7 @@ struct dma_buf_list { > }; > > static struct dma_buf_list db_list; > +static atomic_long_t dma_buf_size; > > static char *dmabuffs_dname(struct dentry *dentry, char *buffer, int buflen) > { > @@ -79,6 +80,7 @@ static void dma_buf_release(struct dentry *dentry) > if (dmabuf->resv == (struct dma_resv *)&dmabuf[1]) > dma_resv_fini(dmabuf->resv); > > + atomic_long_sub(dmabuf->size, &dma_buf_size); > module_put(dmabuf->owner); > kfree(dmabuf->name); > kfree(dmabuf); > @@ -586,6 +588,7 @@ struct dma_buf *dma_buf_export(const struct dma_buf_export_info *exp_info) > mutex_lock(&db_list.lock); > list_add(&dmabuf->list_node, &db_list.head); > mutex_unlock(&db_list.lock); > + atomic_long_add(dmabuf->size, &dma_buf_size); > > return dmabuf; > > @@ -1346,6 +1349,15 @@ void dma_buf_vunmap(struct dma_buf *dmabuf, struct dma_buf_map *map) > } > EXPORT_SYMBOL_GPL(dma_buf_vunmap); > > +/** > + * dma_buf_get_size - Return the used nr pages by dma-buf > + */ > +long dma_buf_get_size(void) > +{ > + return atomic_long_read(&dma_buf_size) >> PAGE_SHIFT; > +} > +EXPORT_SYMBOL_GPL(dma_buf_get_size); > + > #ifdef CONFIG_DEBUG_FS > static int dma_buf_debug_show(struct seq_file *s, void *unused) > { > diff --git a/fs/proc/meminfo.c b/fs/proc/meminfo.c > index 6fa761c9cc78..3c1a82b51a6f 100644 > --- a/fs/proc/meminfo.c > +++ b/fs/proc/meminfo.c > @@ -16,6 +16,7 @@ > #ifdef CONFIG_CMA > #include <linux/cma.h> > #endif > +#include <linux/dma-buf.h> > #include <asm/page.h> > #include "internal.h" > > @@ -145,6 +146,7 @@ static int meminfo_proc_show(struct seq_file *m, void *v) > show_val_kb(m, "CmaFree: ", > global_zone_page_state(NR_FREE_CMA_PAGES)); > #endif > + show_val_kb(m, "DmaBufTotal: ", dma_buf_get_size()); > > hugetlb_report_meminfo(m); > > diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h > index efdc56b9d95f..f6481315a377 100644 > --- a/include/linux/dma-buf.h > +++ b/include/linux/dma-buf.h > @@ -507,4 +507,5 @@ int dma_buf_mmap(struct dma_buf *, struct vm_area_struct *, > unsigned long); > int dma_buf_vmap(struct dma_buf *dmabuf, struct dma_buf_map *map); > void dma_buf_vunmap(struct dma_buf *dmabuf, struct dma_buf_map *map); > +long dma_buf_get_size(void); > #endif /* __DMA_BUF_H__ */

3 years, 8 months

Re: [Linaro-mm-sig] [PATCH] dma-buf: Add DmaBufTotal counter in meminfo

by Matthew Wilcox

On Fri, Apr 16, 2021 at 11:37:19AM +0200, Peter Enderborg wrote: > diff --git a/fs/proc/meminfo.c b/fs/proc/meminfo.c > index 6fa761c9cc78..3c1a82b51a6f 100644 > --- a/fs/proc/meminfo.c > +++ b/fs/proc/meminfo.c > @@ -16,6 +16,7 @@ > #ifdef CONFIG_CMA > #include <linux/cma.h> > #endif > +#include <linux/dma-buf.h> > #include <asm/page.h> > #include "internal.h" > > @@ -145,6 +146,7 @@ static int meminfo_proc_show(struct seq_file *m, void *v) > show_val_kb(m, "CmaFree: ", > global_zone_page_state(NR_FREE_CMA_PAGES)); > #endif > + show_val_kb(m, "DmaBufTotal: ", dma_buf_get_size()); > > hugetlb_report_meminfo(m); > ... and if CONFIG_DMA_SHARED_BUFFER is not set ...?

3 years, 8 months

Re: [Linaro-mm-sig] [RFC] Cross-driver ww transaction lock lists

by Daniel Vetter

On Thu, Apr 15, 2021 at 05:40:24PM +0200, Thomas Hellström (Intel) wrote: > > On 4/15/21 4:40 PM, Daniel Vetter wrote: > > On Thu, Apr 15, 2021 at 4:02 PM Thomas Hellström (Intel) > > <thomas_os(a)shipmail.org> wrote: > > > > > > On 4/15/21 3:37 PM, Daniel Vetter wrote: > > > > On Tue, Apr 13, 2021 at 09:57:06AM +0200, Christian König wrote: > > > > > Am 13.04.21 um 09:50 schrieb Thomas Hellström: > > > > > > Hi! > > > > > > > > > > > > During the dma_resv conversion of the i915 driver, we've been using ww > > > > > > transaction lock lists to keep track of ww_mutexes that are locked > > > > > > during the transaction so that they can be batch unlocked at suitable > > > > > > locations. Including also the LMEM/VRAM eviction we've ended up with > > > > > > two static lists per transaction context; one typically unlocked at the > > > > > > end of transaction and one initialized before and unlocked after each > > > > > > buffer object validate. This enables us to do sleeping locking at > > > > > > eviction and keep objects locked on the eviction list until we > > > > > > eventually succeed allocating memory (modulo minor flaws of course). > > > > > > > > > > > > It would be beneficial with the i915 TTM conversion to be able to > > > > > > introduce a similar functionality that would work in ttm but also > > > > > > cross-driver in, for example move_notify. It would also be beneficial > > > > > > to be able to put any dma_resv ww mutex on the lists, and not require > > > > > > it to be embedded in a particular object type. > > > > > > > > > > > > I started scetching on some utilities for this. For TTM, for example, > > > > > > the idea would be to pass a list head for the ww transaction lock list > > > > > > in the ttm_operation_ctx. A function taking a ww_mutex could then > > > > > > either attach a grabbed lock to the list for batch unlocking, or be > > > > > > responsible for unlocking when the lock's scope is exited. It's also > > > > > > possible to create sublists if so desired. I believe the below would be > > > > > > sufficient to cover the i915 functionality. > > > > > > > > > > > > Any comments and suggestions appreciated! > > > > > ah yes Daniel and I haven been discussing something like this for years. > > > > > > > > > > I also came up with rough implementation, but we always ran into lifetime > > > > > issues. > > > > > > > > > > In other words the ww_mutexes which are on the list would need to be kept > > > > > alive until unlocked. > > > > > > > > > > Because of this we kind of backed up and said we would need this on the GEM > > > > > level instead of working with dma_resv objects. > > > > Yeah there's a few funny concerns here that make this awkward: > > > > - For simplicity doing these helpers at the gem level should make things a > > > > bit easier, because then we have a standard way to drop the reference. > > > > It does mean that the only thing you can lock like this are gem objects, > > > > but I think that's fine. At least for a first cut. > > > > > > > > - This is a bit awkward for vmwgfx, but a) Zack has mentioned he's looking > > > > into adopting gem bo internally to be able to drop a pile of code and > > > > stop making vmwgfx the only special-case we have b) drivers which don't > > > > need this won't need this, so should be fine. > > > > > > > > The other awkward thing I guess is that ttm would need to use the > > > > embedded kref from the gem bo, but that should be transparent I think. > > > > > > > > - Next up is dma-buf: For i915 we'd like to do the same eviction trick > > > > also through p2p dma-buf callbacks, so that this works the same as > > > > eviction/reservation within a gpu. But for these internal bo you might > > > > not have a dma-buf, so we can't just lift the trick to the dma-buf > > > > level. But I think if we pass e.g. a struct list_head and a callback to > > > > unreference/unlock all the buffers in there to the exporter, plus > > > > similar for the slowpath lock, then that should be doable without > > > > glorious layering inversions between dma-buf and gem. > > > > > > > > I think for dma-buf it should even be ok if this requires that we > > > > allocate an entire structure with kmalloc or something, allocating > > > > memory while holding dma_resv is ok. > > > Yes, the thing here with the suggested helpers is that you would just > > > embed a trans_lockitem struct in the gem object (and defines the gem > > > object ops). Otherwise and for passing to dma-buf this is pretty much > > > exactly what you are suggesting, but the huge benefit of encapsulating > > > the needed members like this is that when we need to change something we > > > change it in just one place. > > > > > > For anything that doesn't have a gem object (dma-buf, vmwgfx or > > > whatever) you have the choice of either allocating a struct > > > trans_lockitem or embed it wherever you prefer. In particular, this is > > > beneficial where you have a single dma-resv class ww-mutex sitting > > > somewhere in the way and you don't want to needlessly have a gem object > > > that embeds it. > > The thing is, everyone who actually uses dma_resv_lock has a > > gem_buffer_object underneath. So it feels a bit like flexibility for > > no real need, and I think it would make it slightly more awkard for > > gem drivers to neatly integrate into their cs path. The lockitem > > struct works, but it is a bit cumbersome. > > Well that's partly because of it's impossible to use a standalone ww_mutex > in a locking transaction that can only add gem objects to the list :/. > Already in the i915 driver we have and may want to add various places where > we have dead gem objects sitting because of this. > > Also, more importantly, If we pass a list down the dma-buf move_notify(), a > trans_lockitem is pretty much exactly what we expect back (except of course > for the private pointer). It would be odd if we'd expect all list items to > be gem objects when it's a dma-buf interface? > > > > > Also if we add some wrappers to e.g. add a gem_bo to the ctx, then if > > we decide to slip the lockitem in there, we still only need to touch > > the helper code, and not all drivers. > > Well, yes assuming we always have an embedding gem object for a dma_resv > that might be true, but either way I don't really expect the gem helpers to > look very different. We will need the ops anyway and a specialized context > so if the only thing we're debating is whether or not to embed a struct in > the gem object, unless you really insist on using the gem object initially, > I suggest we try this and if it becomes awkward, just > s/trans_lockitem/drm_gem_object/ Hm yeah I think you convinced me this is a bit a bikeshed :-) Maybe call it dma_resv_lockitem or so if we go with top-level generic solution. And then embed it wheterever we feel like. The annoying thing with tha generic thing is that I'd like to avoid the full callback pointer in all the gem objects, but maybe another ptr really doesn't matter on this if we add a linked list anyway ... -Daniel > > /Thomas > > > > -Daniel -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch

3 years, 8 months

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Linaro-mm-sig April 2021